刺五加制剂对大学生恒定负荷下运动耐力的影响

目的研究刺五加制剂对人体运动能力的影响。方法以10名18~23岁男性大学生为试验对象，以600kg·m/min（100W）功率负荷持速恒定运动测刺五加制剂试服用前后呼出气参数和心率的改变。结果呼吸商由服用前的1．01下降至服用后的0．92，服用刺五加制剂使运动时脂肪供能增加30．6％，心率下降6．6％，每博摄氧量增加5．52％。结论刺五加制剂通过提高人体摄氧能力，增加脂肪供能，节省肌糖元，发挥抗疲劳作用。     

刺五加制剂增强人体运动能力的研究

以16名健康成年男子为试验对象,研究了刺五加制剂对人体运动能力的影响。结果表明服用刺五加制剂后,无氧阈下作功能力由(808±189)kg.m/min(134.0±23.9 W)上升至(904±80)kg.m/min(150.6±19.9 W),提高了12.4%;呼吸商由0.99下降至0.86,使运动时脂肪供能增加43%。乳酸、心率和无氧阈的结果均提示刺五加制剂能提高人体摄氧能力,节省肌糖元,从而发挥抗疲劳作用。     

用药时间对刺五加制剂增强运动耐力的影响

以２０名１８－２３岁男性大学生随机分成持续给药１ｗ组与仅给药一次组，观察持续定量负荷运动时的呼吸商改变。结果发现持续给药１ｗ组在负荷运动时的ＲＱ由０．９３下降至０．９０，脂肪供能增加１０．２％，心率下降了１０．３％，每博摄氧量增加９．８％；而仅给药一次组ＲＱ由０．９４下降至０。９２，脂肪供能仅增加６．８％，其他指标没有明显改变。     

石棉工人运动试验前后SaO2变化的研究

为了探讨石棉工人运动与血氧水平的关系,作者对一批石棉作业工人（简称石棉工人）和对照组进行了运动试验前后ＳａＯ２（动脉血氧饱和度）的监测。结果显示,与对照组相比,石棉工人组运动后ＳａＯ２出现明显下降（Ｐ＜０．０５）;石棉工人组内比较,ＡⅡ组运动后的ＳａＯ２平均下降了９．８％,ＡⅠ组运动后ＳａＯ２平均下降了２．６％,Ａ０组运动后ＳａＯ２平均下降１．５％。运动前后ＳａＯ２的下降值与ＦＶＣ、ＦＥＶ１、ＭＶＶ、ＤＬＣＯ等肺功能指标呈负相关。提示石棉工人运动时摄氧能力减退、血氧水平降低,导致运动能力下降。     

红景天中药复方改善机体骨骼肌能量代谢效果研究

本文为提高高原移居人体劳动能力，研制了以红景天提取物为主，含刺五加、黄芪和丹参的中药复方（９２０４０２复方）。动物随机分为实验组（９２０４０２复方组）和对照组。在小鼠减压缺氧（模拟海拔高度１００００ｍ）游泳实验中，实验组游泳时间明显长于对照组，分别为７５．８±４．４和６２．６±４．４ｍｉｎ，延长约２１．１％（Ｐ＜０．０５）；实验组游泳时间大于６０ｍｉｎ的存活卒明显高于对照组，分别为５５．４％和３６．９％（Ｐ＜０．０５）。在大鼠减压缺氧（模拟海拔高度６０００ｍ）游泳实验中，实验组骨骼肌线粒体ＲＣＲ和ＡＤＰ／Ｏ明显高于对照组（Ｐ＜０．０１），并且ＡＴＰ含量也高于对照组（Ｐ＜０．０５）。结果提示，９２０４０２复方能明显提高缺氧机体运动能力，其机制可能与９２０４０２复方改善缺氧机体骨骼肌能量代谢有关。     

200 mAX线机改造摄高电压尘肺胸片与低电压片读片差异的分析

对２２６例用改造后的２００ｍＡＸ线机所摄高电压胸片与两年内低电压片进行对比，高电压胸片质量明显提高，层次丰富，细微结构清楚，一级片率由０．４％上升为３８．５％，废片率由６．２％下降到０．４％，三、四级合计由７３．０％下降到１２．８％。二者相比原尘肺诊断需改订者占７４．８％，由无尘肺改为Ｉ期者最突出，新检出的７９例尘肺中由０￣＋中检出者占原０￣＋组的９０．６％。表明改机后摄片质量明显改善，影响尘肺诊断，特别是早期者极为明显。     

红景天中药复方提高高原机体劳动能力的效果观察

为提高高原人体劳动能力，研制了以红景天提取物为主，含刺五加、黄芪和丹参的中药复方（９２０４０２复方）。在小白鼠减压缺氧（模拟海拔高度１００００ｍ）游泳实验中，９２０４０２方组游泳时间明显长于对照组，分别为７５．８±４．４和６２．６±４．４ｍｉｎ，延长约２１．１％（Ｐ＜０．０５）；９２０４０２复方组游泳时间大于６０ｍｉｎ的存活率明显高于对照组，分别为５５．４和３６．９％（Ｐ＜０．０５）。在低压舱模拟     

高原健康人运动状态下最大氧耗量无氧代射阈值及心功能…

在海拔３４１７ｍ地区测定了藏汉族少年的最大氧耗量及无氧代射阈。结果：最大耗氧量藏族大于汉族（Ｐ＜０．０５），无氧阈汉族低于藏族（Ｐ＜０．０１）。血氧饱和度随运动负荷的增加而下降，达到最大负荷时藏族下降８．９５％，汉族下降１７．５％。这提示，藏族少年有较最大有氧能力及氧运输能力，显示对高原环境的最佳适应；无氧阈可能被成为评价高原劳动能力的较好指标。     

模拟高原低氧环境下脑-体工作能力研究

实验采用行为功效及劳动能力测定所得分值，为脑－体工作能力定量评分。实验模型为人体在减压舱模拟３５００ｍ和４５００ｍ的低氧环境。结果显示，在３５００ｍ和４５００ｍ，工作能力得分较３００ｍ平原降低了１７．９％和３３．７％，且以体能下降为主，两个高度体能的降幅分别是２３．７％和３１．２％（Ｐ＜０．０５）。脑力活动显著受抑是在４５００ｍ，降幅为２０．４％（Ｐ＜０．０５）。结果说明低氧与工作能力下降有明显量效关系。     

刺五加对冷适应大鼠红细胞膜Na~＋、K~＋－ATP酶活性的影响

用刺五加口服液给大鼠灌胃，在其冷适应的过程中，检测其红细胞膜Ｎａ＋、Ｋ＋－ＡＴＰ酶活性的变化。结果表明：灌胃７、１４、２１天时，给药组与暴寒组相比．红细胞膜Ｎａ＋、Ｋ＋－ＡＴＰ酶活性明显增加（Ｐ＜０．０５）。说明刺五加可以调整机体细胞的代谢，对提高机体耐寒能力有一定的作用。     

刺五加制剂对小鼠的抗疲劳作用

采用小鼠游泳试验系统地研究了刺五加制剂对小鼠抗疲劳作用的影响。口服刺五加制剂0.8g/kg 剂量组与人参0.8g/kg 剂量组相当,可使游泳时间延长60%;1.6g/kg 为适宜剂量,游泳时间延长132%。无论一次给药还是持续给药,刺五加制剂均有增强小鼠运动耐力的作用(游泳时间分别延长65%和100%～120%),然而持续给药比一次给药抗疲劳效应更强。人参和冬虫夏草与刺五加制剂复合给药,均使刺五加制剂抗疲劳效应降低。     

Two Minutes of Sprint-Interval Exercise Elicits 24-hr Oxygen Consumption Similar to That of 30 min of Continuous Endurance Exercise

Six weeks (3 times/wk) of sprint-interval training (SIT) or continuous endurance training (CET) promote body-fat losses despite a substantially lower training volume with SIT. In an attempt to explain these findings, the authors quantified VO2 during and after (24 h) sprint-interval exercise (SIE; 2 min exercise) vs. continuous endurance exercise (CEE; 30 min exercise). VO2 was measured in male students (n = 8) 8 times over 24 hr under 3 treatments (SIE, CEE, and control [CTRL, no exercise]). Diet was controlled. VO2 was 150% greater (p < .01) during CEE vs. SIE (87.6 ± 13.1 vs. 35.1 ± 4.4 L O2; M ± SD). The observed small difference between average exercise heart rates with CEE (157 ± 10 beats/min) and SIE (149 ± 6 beats/min) approached significance (p = .06), as did the difference in peak heart rates during CEE (166 ± 10 beats/min) and SIE (173 ± 6 beats/min; p = .14). Total O2 consumed over 8 hr with CEE (263.3 ± 30.2 L) was greater (p < .01) than both SIE (224.2 ± 15.3 L; p < .001) and CTRL (163.5 ± 16.1 L; p < .001). Total O2 with SIE was also increased over CTRL (p < .001). At 24 hr, both exercise treatments were increased (p < .001) vs. CTRL (CEE = 500.2 ± 49.2; SIE = 498.0 ± 29.4; CTRL = 400.2 ± 44.6), but there was no difference between CEE and SIE (p = .99). Despite large differences in exercise VO2, the protracted effects of SIE result in a similar total VO2 over 24 hr vs. CEE, indicating that the significant body-fat losses observed previously with SIT are partially due to increases in metabolism postexercise.     

A scientific nutrition strategy improves time trial performance by ≈6% when compared with a self-chosen nutrition strategy in trained cyclists: a randomized cross-over study

We investigated whether an athlete's self-chosen nutrition strategy (A), compared with a scientifically determined one (S), led to an improved endurance performance in a laboratory time trial after an endurance exercise. S consisted of about 1000 mL·h(-1) fluid, in portions of 250 mL every 15 min, 0.5 g sodium·L(-1), 60 g glucose·h(-1), 30 g fructose·h(-1), and 5 mg caffeine·kg body mass(-1). Eighteen endurance-trained cyclists (16 male; 2 female) were tested using a randomized crossover-design at intervals of 2 weeks, following either A or S. After a warm-up, a maximal oxygen uptake test was performed. Following a 30-min break, a 2.5-h endurance exercise on a bicycle ergometer was carried out at 70% maximal oxygen uptake. After 5 min of rest, a time trial of 64.37 km (40 miles) was completed. The ingested nutrition was recorded every 15 min. In S, the athletes completed the time trial faster (128 vs. 136 min; p ≤ 0.001) and with a significantly higher power output (212 vs. 184 W; p ≤ 0.001). The intake of fluid, energy (carbohydrate-, mono-, and disaccharide), and sodium was significantly higher in S compared with A (p ≤ 0.001) during the endurance exercise. In the time trial, only sodium intake was significantly higher in S (p ≤ 0.001). We concluded that a time trial performance after a 2.5-h endurance exercise in a laboratory setting was significantly improved following a scientific nutrition strategy.     

Short-term (-)-hydroxycitrate ingestion increases fat oxidation during exercise in athletes

(-)-Hydroxycitrate (HCA) is known to inhibit increasing malonyl CoA concentration during endurance exercise. Furthermore, a short-term administration of HCA enhances endurance exercise performance in mice. Therefore we investigated the short-term administration of HCA on the exercise performance of athletes. Subjects were administered 250 mg of HCA or placebo as a control (CON) for 5 d, after each time performing cycle ergometer exercise at 60% VO2max for 60 min followed by 80% VO2max until exhaustion. Blood was collected and expired gas samples analyzed at rest and every 15 min. The respiratory exchange ratio was significantly lower in the HCA trial than in the CON trial (p < 0.05). Fat oxidation was significantly increased by short-term administration of HCA, and carbohydrate oxidation was significantly decreased (p < 0.05) during exercise, presumably resulting in increasing the cycle ergometer exercise time to exhaustion after 1 h of 60% VO2max exercise (p < 0.05). These results suggest that a short-term administration of HCA enhances endurance performance with increasing fat oxidation, which spares glycogen utilization during moderate intensity exercise in athletes.     

Dietary composition influences short-term endurance training-induced adaptations of substrate partitioning during exercise

The purpose of the current study was to examine the influence of dietary composition on short-term endurance training-induced adaptations of substrate partitioning and time trial exercise performance. Eight untrained males cycled for 90 min at approximately 54% aerobic capacity while being infused with [6,6(2)H]glucose before and after two 10-d experimental phases separated by a 2-week washout period. Time trial performance was measured after the 90-min exercise trials before and after the 2nd experimental phase. During the first 10-d phase, subjects were randomly assigned to consume either a high carbohydrate or high fat diet while remaining inactive (CHO or FAT). During the second 10-d phase, subjects consumed the opposite diet, and both groups performed identical daily supervised endurance training (CHO+T or FAT+T). CHO and CHO+T did not affect exercise metabolism. FAT reduced glucose flux at the end of exercise, while FAT+T substantially increased whole body lipid oxidation during exercise and reduced glucose flux at the end of exercise. Despite these differences in adaptation of substrate use, training resulted in similar improvements in time trial performance for both groups. We conclude that (a) 10-d high fat diets result in substantial increases in whole body lipid oxidation during exercise when combined with daily aerobic training, and (b) diet does not affect short-term training-induced improvements in high-intensity time trial performance.     

Effects of endurance training on blood lactate, plasma noradrenaline, heart rate, and systolic blood pressure at submaximal exercise

The purpose of this study was to investigate the effects of low-intensity endurance training on the lactate threshold (LT) and the onset of blood lactate accumulation (OBLA), as well as the relationship among blood lactate, heart rate, systolic blood pressure and the plasma noradrenaline (NA) concentration during submaximal exercise before and after training. Seven middle-aged women aged 33-57 years performed endurance training on a bicycle ergometer for 60 min 3 days a week for 6 weeks at an intensity corresponding to 50% of their maximum oxygen uptake. The results were summarized as follows: 1) LT and OBLA increased significantly by 32% (p less than 0.05) and 16% (p less than 0.05), respectively, after the training. 2) The increase rate of OBLA correlated negatively to its initial level (p less than 0.05) but the increase rate of LT did not. 3) Heart rate, systolic blood pressure and the pressure rate product (systolic blood pressure x heart rate x 10(-2] at LT and OBLA did not change significantly after the training. 4) A significant linear correlation between blood lactate and NA was observed during the submaximal exercise before (p less than 0.05) and after (p less than 0.05) the training, but the slopes of the two regression lines did not differ significantly. It was concluded that low-intensity training results in a significant improvement in LT and OBLA for middle-aged women. It was further suggested that, after the training, diminished responses of the cardiovascular and sympathetic nervous system are in parallel with the decrease in the blood lactate concentration during submaximal exercise.     

Caffeine as a lipolytic food component increases endurance performance in rats and athletes

Caffeine is one of the famous ergogenic aids in the athletic field. Caffeine has been known to stimulate lipolysis that spares stored glycogen utilization during moderate intensity exercise. Therefore, we investigated the effects of caffeine ingestion on exercise performance in rats and athletes. Rats were administered the caffeine (6 mg/kg) 1 h prior to the exercise then were run on a treadmill at a speed of 20 m/min. They were decapitated at 0 min, 30 min, 60 min of exercise, and exhausted time point. Human subjects ingested the caffeine (5 mg/kg) 1 h prior to the exercise. They exercised on a cycle ergometer at 60% of their VO2max for 45 min, and then the exercise intensity was increased to 80% of their VO2max until exhaustion. Blood and breathing gas samples were collected and calculated every 10 min during exercise. Respiratory exchange ratio of the caffeine trial was significantly lower than that of the placebo trial in the athletes' study (p<0.05). Blood free fatty acid (FFA) levels in studies of both rats and athletes were increased by caffeine ingestion during exercise (p<0.05). Blood lactate levels were also increased during exercise in both rats and athletes (p<0.05). Increased FFA and glycerol concentrations reduced glycogen utilization during exercise compared with placebo group in rats. In addition, endurance time to exhaustion was significantly increased by the caffeine ingestion in both rats and athletes (p<0.05). These results suggest that the caffeine ingestion enhanced endurance performance resulting from spare stored glycogen with increasing lipolysis from adipose tissues and fat oxidation during exercise both in rats and in athletes.     

Riboflavin requirements and exercise adaptation in older women.

The effects of exercise training on riboflavin requirements and of riboflavin intake on endurance were examined in 14 women, 50-67 y of age, who participated in a 10-wk, two-period crossover exercise study at two riboflavin intakes, 0.15 micrograms/kJ (0.6 micrograms/kcal) and 0.22 micrograms/kJ (0.9 micrograms/kcal). Subjects exercised 20-25 min/d, 6 d/wk, for 4-wk periods on a cycle ergometer at 75-85% of their maximal heart rate. Riboflavin status was assessed by measuring the erythrocyte glutathione reductase activity coefficient (EGRAC) and urinary riboflavin excretion. Physical performance was evaluated by using a walking treadmill test to determine maximal oxygen capacity (VO2max) and anaerobic threshold by gas exchange (ATGE). Exercise significantly affected riboflavin status as EGRAC increased (P less than 0.001) and riboflavin excretion decreased (P less than 0.01) in both groups. VO2max increased significantly with exercise (P less than 0.01). However, changes in VO2max (L/min) and ATGE with exercise training were not different in the two groups. Riboflavin requirements of older women increased with exercise training, but increased riboflavin intake did not enhance improvements in endurance.     

A role for branched-chain amino acids in reducing central fatigue

Several factors have been identified to cause peripheral fatigue during exercise, whereas the mechanisms behind central fatigue are less well known. Changes in the brain 5-hydroxytryptamine (5-HT) level is one factor that has been suggested to cause fatigue. The rate-limiting step in the synthesis of 5-HT is the transport of tryptophan across the blood-brain barrier. This transport is influenced by the fraction of tryptophan available for transport into the brain and the concentration of the other large neutral amino acids, including the BCAAs (leucine, isoleucine, and valine), which are transported via the same carrier system. Studies in human subjects have shown that the plasma ratio of free tryptophan (unbound to albumin)/BCAAs increases and that tryptophan is taken up by the brain during endurance exercise, suggesting that this may increase the synthesis of 5-HT in the brain. Ingestion of BCAAs increases their concentration in plasma. This may reduce the uptake of tryptophan by the brain and also 5-HT synthesis and thereby delay fatigue. Accordingly, when BCAAs were supplied to human subjects during a standardized cycle ergometer exercise their ratings of perceived exertion and mental fatigue were reduced, and, during a competitive 30-km cross-country race, their performance on different cognitive tests was improved after the race. In some situations the intake of BCAAs also improves physical performance. The results also suggest that ingestion of carbohydrates during exercise delays a possible effect of BCAAs on fatigue since the brain's uptake of tryptophan is reduced.